All of Lumiere's liquid crystal comes from some space inside him, and so all of it connects back to that space. If you navigate correctly, you can warp between different surfaces of liquid, no matter what the distance.
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That's easier said than done though, cause the portals necessarily don't link up in an A to B fashion, or even in a way that makes intuitive sense sometimes..! It's a labyrinth in there that only Lumiere knows the full layout of haha

(That also implies that he might have eyes in all those spots where the surfaces are too. Spoooky..!)